Sterile suspensions of slightly soluble basic peptide complexes and pharmaceutical formulations containing them

ABSTRACT

The invention provides sterile suspensions and sterile lyophilizates of slightly soluble basic peptide complexes, and pharmaceutical formulations comprising them. The provided sterile suspensions, sterile lyophilizates and pharmaceutical formulations comprising them are particularly suitable for use in a parenteral dosage form as medicaments for the treatment and prophylaxis of diseases and pathological states in mammals, especially in humans.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of prior U.S. patent application Ser. No. 11/304,548, filed Dec. 16, 2005, which claims priority to U.S. Provisional applications 60/637,770 filed Dec. 22, 2004, and 60/741,911 filed Dec. 5, 2005, all incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a novel process for producing sterile suspensions and sterile lyophilizates of slightly soluble basic peptide complexes. The invention further relates to sterile suspensions and sterile lyophilizates, and to pharmaceutical formulations which comprise one or more lyophilizates, preferably produced according to the invention, of slightly soluble basic peptide complexes. The suspensions and lyophilizates produced according to the invention can be used as medicaments for example for the treatment of benign or malignant neoplastic diseases, in hormone therapy, for the treatment of fertility disorders and for contraception, for the treatment of HIV infections and for the treatment of neurological or neurodegenerative disorders.

BACKGROUND OF THE INVENTION

Sufficiently high bioavailability and, as a consequence, therapeutic efficacy of peptides is frequently ensured only by parenteral administration, because peptides undergo proteolytic degradation after oral administration, only low absorption takes place nasally, and no absorption takes place dermally. Because of the low half-life of peptides in the body, parenteral administration of peptide medicaments, e.g. luteinizing hormone releasing hormone (LHRH) analogs such as the so-called superagonists, for example goserelin (INN), leuprorelin (INN) or triptorelin (INN), and LHRH antagonists such as, for example, antide (INN), cetrorelix (INN), degarelix (INN) or ganirelix (INN), must take place each day within a therapy period in order to achieve and maintain the desired suppressant effects on luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

The result of this suppression in men is the reduction in the production and release of testosterone and in women there is a reduction in the production and release of estradiol, it being perfectly possible for the degree of reduction required to vary between the medical indications. Lowering the blood levels of sex hormones is a standard therapy in the palliative treatment of sex hormone-sensitive tumors, for which a permanent reduction to a low level (castration) is necessary. It is also standard therapy for the treatment of benign gynacological or urological disorders, e.g. endometriosis, uterine leiomyomas, uterine fibroids and benign prostate hyperplasia (BPH), for the treatment of fertility impairments and for contraception, it also being possible in these cases, depending on the therapeutic strategy, for intermittent partial reduction of the sex hormone levels to be sufficient.

The need for depot formulations which can be administered parenterally for long-lasting and controlled release of peptide medicaments, making the need for daily administrations obsolete, was recognised a relatively long time ago.

DE 38 22 459 A1 discloses pharmaceutical formulations which comprise complexes of water-insoluble peptides, such as, for example, LHRH analogs, with embonic, tannic and stearic acid and biodegradable lactic acid-glycol acid copolymers. In the production process disclosed therein, chlorinated hydrocarbons such as dichloromethane are employed as solvents and subsequently removed for the most part by rotary evaporation. However, the use of such potentially carcinogenic solvents is disadvantageous because of the high residual solvent content, e.g. ˜4500 ppm dichloromethane (Koushik K and Kompella U B, Pharmaceutical Research, 2004, 21: 524-535), in pharmaceutical forms produced by solvent evaporation. The ICH guideline “Impurities: Guideline for Residual Solvents—Q3C” strictly limits the residual solvent content for class 2 solvents in pharmaceutical products for reasons of drug safety, e.g. for the chlorinated hydrocarbons dichloromethane and chloroform to respectively 600 ppm and as low as 60 ppm. A further crucial disadvantage is the rotary evaporation of the volatile toxic solvent because of the risk of contamination and explosion. Use of chlorinated hydrocarbons in the production process additionally represents a hazard for employees and the environment. Sterility of the pharmaceutical formulations is achieved only by a subsequent gamma irradiation. Besides the aspects of considerable additional costs and increased potential hazards for employees and the environment, subsequent gamma irradiation also leads however, because of the higher radiation dose (25 kGy according to Ph. Eur.), to increased decomposition and therefore has a disadvantageous effect on the stability of such formulations. In addition, the use of gamma irradiation represents a particular obstacle to authorization with elaborate qualification and validation requirements (see: EC Guide to Good Manufacturing Practice—Annex 12).

U.S. Pat. No. 5,134,122 describes the production of microparticles of a lactic acid-glycolic acid copolymer which comprise, as pharmaceutically active substance, peptides in the form of their water-insoluble embonate, tannate, stearate or palmitate salts. However, the process described therein requires the disadvantageous use of special elaborate extrusion machines and a thermal treatment at up to 100° C., which may lead to destruction of the peptides and to a greater level of contamination of the pharmaceutical form by increased degradation or condensation products. A further disadvantage of the process is the need to sieve the microparticles in order to obtain the desired particle size. Such a sieving step is scarcely possible in an aseptic production process in a clean room because of the potential particle contamination (see: EC Guide to good Manufacturing Practice—Annex 1).

DE 42 23 282 A1 and DE 42 23 284 A1 (and U.S. Pat. No. 5,445,832 and U.S. Pat. No. 5,637,568 as US patents belonging to the patent family) describe processes for producing pharmaceutical preparations in which water-insoluble medicamentous peptide substances are incorporated into microparticles of a biodegradable polymeric material. Both processes have the already described disadvantage of the obligatory use of carcinogenic chlorinated hydrocarbons and the problem of physiologically unacceptable residual solvent contents. A further disadvantage is the low percentage loading of the microparticles with active ingredient, and the already discussed gamma irradiation.

DE 43 42 092 A1 (and U.S. Pat. No. 5,773,032 as US patent belonging to the patent family) discloses the nonsterile production of slightly soluble salts of peptide LHRH analogs by reacting an aqueous solution of the acid salt with an acetic acid solution of the LHRH analog base to precipitate the slightly soluble acid addition salt, and the use thereof as medicaments. One disadvantage of this process is, however, the obligatory filtration step which, on the pilot and production scale, on use of, for example, 30 g of peptide in the batch, leads to the formation of inhomogeneous gelatinous peptide precipitates which cannot be resuspended and cause intolerable long filtration times. In addition, the filtration is associated with a disadvantageous coprecipitation of alkaline earth metal and alkali metal salts, such as, for example, sodium acetate, which may promote decomposition of the peptide salt, and may lead to tolerability problems occurring in patients on parenteral administration. Further disadvantages of this production process are the use of organic solvents such as dimethylacetamide and dimethyl acetate, with the already described problem of the residual solvent content, and the necessary sieving step which is scarcely possible, as already mentioned above, on aseptic production in a clean room. In addition, the salts and suspensions described in DE 43 42 092 A1 and produced by the disclosed process are not sterile, because the process described therein and including the process steps of ‘filtration’ and ‘drying’ cannot industrially result in intrinsically sterile process products (there: dried filter cake as precipitate), thus making for example direct parenteral administration, but also further processing in an aseptic process, impossible.

The lacking sterility, which is an obligatory requirement for aseptic further processing and administration of such salts and suspensions as medicaments, could be achieved only by an additional sterilization step, which is not disclosed in DE 43 42 092 A1, by gamma irradiation.

As already discussed above, however, subsequent gamma irradiation leads, because of the high radiation dose, to an increased decomposition and therefore has disadvantageous effects on the stability of such salts and suspensions, besides the aspects of considerable additional costs, increased potential hazards for employees and the environment and elaborate qualification and validation measures. In addition, the salts produced according to DE 43 42 092 A1 are in the form of microparticles with which it is not possible to generate suspensions which are stable for a prolonged period without, or even with, addition of additives which increase the viscosity and assist resuspendability. Although it is possible to generate a suspension, e.g. in aqueous solution, with continuous mixing, it corresponds rather to an agitation of the solid microparticles in the liquid phase. If the mixing is stopped or interrupted, a two-phase mixture quickly forms again and consists of solid phase (microparticles) and liquid phase (aqueous solution) separate from one another.

Felberbaum et al. (Human Reproduction, 1998, 13: 1660-1668) describe the use of the cetrorelix embonate microparticles produced according to DE 43 42 092 A1 in the treatment of uterine fibromas. A sterile suspension of the microparticles treated by gamma irradiation, in which the microparticles were resuspended in an aqueous solution with the addition of polysorbate 80, sodium hydroxide solution and carboxymethylcellulose (CMC), was employed. However, as already indicated above, such a formulation of cetrorelix embonate microparticles does not represent a suspension which is stable for a prolonged period even with addition of additives which increase the viscosity and assist resuspendability; on the contrary it quickly separates again to a two-phase mixture composed of liquid and solid phase separate from one another.

Additionally, however, the addition of viscosity-increasing CMC represents a considerable disadvantage because CMC may lead, especially on parenteral administration, to allergic reactions or even anaphylaxis (Bigliardi et al., Dermatology 2003, 207:100-103; Oppliger and Hauser, JDDG 2004, 2:928-930), and should therefore be avoided. Furthermore, administration of the microparticle suspension led to inadequate estradiol suppression in some patients. On the other hand, in other patients there was a reduction in the estradiol level to distinctly below 20 pg/ml and thus an unwanted chemical castration (see also: Kaufmann et al., Journal of Clinical Oncology 1989, 7: 1113-1119; Battaglia et al., Gynecological Endocrinology 1995, 9: 143-148; Reron et al., Neuroendocrinology Letters 2002, 23: 455-458) with the corresponding hormone withdrawal manifestations which are disadvantageous for the patients. The authors themselves speak of the need for an improved formulation which avoids the observed disadvantages.

DE 100 40 700 A1 (and U.S. Pat. No. 6,780,972, US 2002/198146 and US 2004/259801 as US patents belonging to the patent family) describes a process for producing slightly soluble peptide salts, in which the dissolved initial peptide salt of a basic peptide is reacted with a mixed bed ion exchanger or a mixture of an acidic and basic ion exchanger to form the free basic peptide, subsequently the ion exchanger is removed, the free basic peptide is reacted with an acid to form the final peptide salt, and finally the solvent is removed. The process disclosed therein has the disadvantage, however, that nonsterile ion exchangers not complying with GMP guidelines must be used and represent, because of organic residues such as sulfonic acid residues and microbiological residues, a potential source of contamination. Thus, the microbiological load of the inner cavities of the nonsterile ion exchanger particles cannot be ascertained straightforwardly before use. The use of such ion exchangers represents an unacceptable and unpredictable risk of contamination of the peptide complexes to be prepared because of possible mechanical damage or possible destruction of the particles during the reaction process, such as, for example, by stirring or shaking. A further disadvantage is the instability of the free peptide base in basic solution, which leads to increased decomposition products in only a short time, e.g. after only 10 minutes, which would according to the ICH guideline “Impurities in New Drug Products—Q3B(R)” make elaborate identification and qualification measures necessary for the suspensions disclosed in the patent. This disadvantageous decomposition can only partly be counteracted by a large molar excess of ion exchanger, which in turn entails the disadvantage of lower product yields (approx. 15-20% loss of yield) in the reaction. A further disadvantage of the disclosed process is the increased thermal stress on the slightly soluble peptide salts due to the need to remove the solvent by distillation, which likewise leads to increased decomposition products and thus a greater degree of contamination in the pharmaceutical form. In addition, removal of volatile solvents by distillation is scarcely possible in a clean room area because of the risk of contamination and explosion. Moreover, the suspensions produced by the disclosed process are not necessarily sterile and may even, for the reasons mentioned above, be microbiologically contaminated. With sparingly soluble peptide salts prepared by the process of DE 100 40 700 A1 there is accordingly always a need before use for parenteral administration that they be sterilized, for example by gamma irradiation, which is associated with the disadvantages already described.

DESCRIPTION OF THE INVENTION

The present invention therefore has the object of providing a novel process which makes it possible to produce sterile suspensions and sterile lyophilizates of slightly soluble basic peptide complexes and moreover to avoid the disadvantages, described above, of the known processes, such as gamma sterilization, the use of toxic organic solvents, the generation of peptide salt particles which are difficult to resuspend etc. A further object of the invention is the provision of sterile suspensions of such slightly soluble basic peptide complexes, which can be directly administered parenterally or directly processed further in an aseptic production process, e.g. by lyophilization, and the provision of corresponding sterile lyophilizates of such slightly soluble basic peptide complexes.

The object of the invention has been achieved in one aspect in a surprising manner by providing a novel process for producing sterile suspensions of slightly soluble basic peptide complexes, that comprises, under aseptic conditions,

-   a) i) mixing a sterile solution comprising     -   a salt or a complex of a basic peptide and     -   an aliphatic or aromatic organic carboxylic acid and/or salts         thereof in a solvent or solvent mixture, optionally with the         addition of solubility-increasing and/or         agglomeration-suppressing additives, or     -   ii) combining and mixing a sterile solution of a salt or complex         of a basic peptide in a solvent or solvent mixture and a sterile         solution of an aliphatic or aromatic organic carboxylic acid         and/or salts thereof in a solvent or solvent mixture, optionally         with the addition of solubility-increasing and/or         agglomeration-suppressing additives, -   b) generating, by mixing and addition of a diluent or diluent     mixture in one or more steps, a suspension of a slightly soluble     basic peptide complex of the basic peptide with the carboxylic acid,     which complex precipitates at the latest after addition of the     diluent or diluent mixture, -   c) depleting, while mixing in a continuous or stepwise separation     process, the solvent or solvent mixture, the free non-peptide ions,     the excess carboxylic acid and the optionally added     solubility-increasing and/or agglomeration-suppressing additives in     the resulting suspension, with the liquid content of the suspension     being reduced and optionally further diluent or diluent mixture     being added in one or more steps, and -   d) adding, while mixing the sterile suspension thus obtained, the     slightly soluble basic peptide complex, optionally pharmaceutical     excipients, carriers and/or bulking agents.

In a preferred embodiment, the above-described process for producing sterile suspensions of slightly soluble basic peptide complex comprises the sterile solution of the salt or complex of the basic peptide and the sterile solution of the aliphatic or aromatic organic carboxylic acid and/or salts thereof being present in the same solvent or solvent mixture in step a) ii).

In a further aspect, the object of the invention has surprisingly been achieved by providing a novel process for producing sterile lyophilizates of slightly soluble basic peptide complexes, that comprises lyophilizing the sterile suspension of the slightly soluble basic peptide complex which has been obtained in steps c) or d) of the process just described for producing sterile suspensions of slightly soluble basic peptide complexes, and optionally adding pharmaceutical excipients, carriers and/or bulking agents to the lyophilizate obtained.

In a further aspect, the object of the invention has surprisingly been achieved by providing a novel process for producing sterile suspensions, suitable for parenteral administration, of slightly soluble basic peptide complexes, which comprises reconstituting the lyophilizate of the slightly soluble basic peptide complex which has been obtained by the process just described for producing sterile lyophilizates of slightly soluble basic peptide complexes with a sterile physiologically tolerated reconstituting medium.

In a further aspect, the object of the invention has surprisingly been achieved by providing sterile suspensions of a slightly soluble basic peptide complex obtainable by the process just described for producing sterile suspensions of slightly soluble basic peptide complexes and processes for producing sterile suspensions, suitable for parenteral administration, of slightly soluble basic peptide complexes.

In a further aspect, the object of the invention has surprisingly been achieved by providing sterile lyophilizates of a slightly soluble basic peptide complex obtainable by the process just described for producing sterile lyophilizates of slightly soluble basic peptide complexes.

The term “basic peptide” means for the purposes of this invention peptides consisting of 2-50 naturally occurring and/or synthetic amino acids, preferably 5-20 amino acids, particularly preferably 9-10 amino acids, which comprise one or more basic amino acids such as, for example, arginine, histidine, pyridylalanine or lysine, and/or at least one basic group, for example a primary, secondary or tertiary amino group, such as, for example, the groups “—NH₂”, “—NHR” or “—NR₂”, where R is selected from the group consisting of “alkyl, alkyloxy, aryl, heteroaryl, aralkyl, heteroaralkyl, aralkyloxy, heteroaralkyloxy” (as described in U.S. Pat. No. 5,942,493) and have overall a basic character.

Preferred basic peptides are LHRH analogs, and those particularly preferred are the so-called LHRH superagonists goserelin, leuprorelin, triptorelin and the LHRH antagonists antide, A-75998, cetrorelix, ozarelix [D-63153, Ac-D-Nal(2)-4-Cl-D-Phe-D-Pal(3)-Ser-N-Me-Tyr-D-HCl-Nle-Arg-Pro-D-Ala-NH₂; where Nal(2) means 2-naphthylalanine, Pal(3) means 3-pyridylalanine, Me means methyl, HCl means homocitrulline and Nle means norleucine], degarelix, ganirelix, NaI-Glu antagonist, teverelix (Antarelix®), and the antagonists according to the compounds: the compounds disclosed in the patent application U.S. Pat. No. 5,942,493, of the general formula (I)

in which n is the number 3 or 4, R1 is an alkyl group, an alkoxy group, an aryl group, a heteroaryl group, an aralkyl group, a heteroaralkyl group, an aralkyloxy group or a heteroaralkyloxy group, in each case unsubstituted or substituted, R2 and R3 are independently of one another each a hydrogen atom, an alkyl group, an aralkyl group or a heteroaralkyl group, in each case unsubstituted or substituted, where the substitution in turn may consist of an aryl group or heteroaryl group, or —NR²R³ is an amino acid group, and R4 is a group having the formula (II)

in which p is an integer from 1 to 4, R5 is hydrogen or an alkyl group and R⁶ is an unsubstituted or substituted aryl group or heteroaryl group, or R4 is a ring of the general formula (III)

in which q is the number 1 or 2, R7 is a hydrogen atom or an alkyl group, R8 is a hydrogen atom or an alkyl group and X is an oxygen or sulfur atom, where the aromatic or heteroaromatic radicals may be partly or completely hydrogenated and chiral carbon atoms may have the R or S configuration,

the LHRH antagonists according to the compounds of the general formula (IV)

Ac-D-Nal(2)-D-(pCl)Phe-D-Pal(3)-Ser-Tyr-D-Xxx-Leu-Arg-Pro-D-Ala-NH₂  (IV)

in which D-Xxx is an amino acid group of the general formula (V)

in which n is the number 3 or 4, R4 is a group having the formula (VI)

in which p is an integer from 1 to 4, R5 is hydrogen or an alkyl group and R6 is an unsubstituted or substituted aryl group or heteroaryl group, or R4 is a ring of the general formula (VII)

in which q is the number 1 or 2, R7 is a hydrogen atom or an alkyl group, R8 is a hydrogen atom or an alkyl group and X is an oxygen or sulfur atom, and

the LHRH antagonists according to the compounds of the following general formula (VIII)

A-Xxx¹-Xxx²-Xxx³-Xxx⁴-Xxx⁵-Xxx⁶-Xxx⁷-Xxx⁸-Xxx⁹-Xxx¹⁰—NH₂  (VIII)

in which A is an acetyl or a 3-(4-fluorophenyl)propionyl group,

Xxx¹ is D-Nal(1) or D-Nal(2),

Xxx²-Xxx³ is D-Cpa-D-Pal(3) or a single bond,

Xxx⁴ is Ser, Xxx⁵ is N-Me-Tyr,

Xxx⁶ is D-Cit, D-Hci or a D-amino acid group of the general formula (IX)

in which n is the number 3 or 4, where R1 is a group having the general formula (X)

—(CH₂)_(p)—CO—NR2R3  (X)

in which p is an integer from 1 to 4, R2 is hydrogen or an alkyl group and R3 is an unsubstituted or substituted aryl group or heteroaryl group, and R1 is a 3-amino-1,2,4-triazole-5-carbonyl group or R1 is a ring of the general formula (XI)

in which q is the number 1 or 2, R4 is a hydrogen atom or an alkyl group, R5 is a hydrogen atom or an alkyl group and X is an oxygen or sulfur atom,

Xxx⁷ is Leu or Nle, Xxx⁸ is Arg or Lys(IPr), Xxx⁹ is Pro and Xxx¹⁰ is Ala or Sar.

Further peptides are abarelix, azaline B, detirelix, ramorelix and RS-68439. The structures of said peptides are to be found inter alia in: Behre et al., GnRH antagonists: an overview, Proceedings of the 2nd World Conference on Ovulation Induction, The Parthenon Publishing Group Ltd.; Kutscher et al., Angew. Chem. 1997, 109, 2240; Stoeckemann and Sandow, J. Cancer Res. Clin. Oncol. 1993, 119, 457.

The LHRH antagonists particularly preferred for the purposes of the present invention are cetrorelix, ozarelix (D-63153) and teverelix (Antarelix®).

The terms “basic character” and “basic” relating to basic peptide means for the purposes of this invention that the pure peptide, i.e. the pure peptide base without salt adducts and/or other additions, has a pH greater than 7.00 as saturated solution in water under standard conditions.

Standard conditions mean the temperature of about 22° C. known to the skilled worker, and the atmospheric pressure of about 1000 hPa (10⁵ Pa), with normal variations such as, for example, weather- and season-related changes also to be taken into account.

The starting material employed in the process of the present invention in step a) is normally not the free base of the basic peptide, owing to its lack of stability and solubility, but a salt or a complex of the basic peptide. This salt employed as starting material or this complex employed as starting material is usually a salt which is soluble in a suitable solvent or solvent mixture, or a soluble complex. Solvents or solvent mixtures suitable for the purposes of the present invention are detailed below.

In a preferred embodiment, the salt employed in step a) or the complex of the basic peptide in the process according to the invention is a salt which is not slightly soluble or a complex which is not slightly soluble, preferably a salt or complex selected from the group consisting of: “acetate, hydrochloride, chloride, fluoride, bromide, iodide, gluconate, glucuronate, trifluoroacetate, glutamate, lactate, phosphate, hydrogen phosphate, dihydrogen phosphate, aspartate, succinate, tartrate”.

The term “basic peptide complex” includes according to the invention the combination of two or more components to form a system which need not be subject to any definite stoichiometry and in which at least one component is a basic peptide and at least one component is an aliphatic or aromatic organic carboxylic acid, where the combination of the components is caused by a superimposition of interactions involving mainly secondary valence linkages but also ionic interactions.

Thus, the molar ratio of basic peptide to carboxylic acid in the basic peptide complex may assume for example all values between 100:1 and 1:100, preferably between 20:1 and 1:20, more preferably between 5:1 and 1:5 and particularly preferably between 2:1 and 1:2.

The basic peptide complex need not, in contrast to the basic peptide, itself have any basic character or be basic. It may for example also have a pH of less than or equal to 7.00.

The slightly soluble peptide complex of the basic peptide with the carboxylic acid which is generated in step b) of the process described above results from reaction of the starting materials dissolved in the one sterile solution after step a) i) or the two sterile solutions after step a) ii) of the process and differs from the salt or complex, dissolved therein, of a basic peptide. This reaction is normally a chemical reaction, for example a conventional metathesis, whose equilibrium can be shifted for example because of the slight solubility in the direction of the resulting and precipitating basic peptide complex.

The starting materials, i.e. the salt or the complex of a basic peptide and the aliphatic or aromatic organic carboxylic acid and/or salts thereof can, before carrying out step a) of the process described above, or for its preparation, optionally be dissolved together [as in step a) i)] or separately from one another [as in step a) ii)] in the same or different solvents or solvent mixtures and be sterilized. If the solutions are prone to premature precipitation on mixing or if premature formation of a suspension occurs, and therefore sterilizing filtration can no longer be carried out, preference is to be given to step a) according to variant a) ii).

In a further preferred embodiment, the processes according to the invention comprise a sterile solution comprising a salt or complex of a basic peptide and an aliphatic or aromatic organic carboxylic acid and/or salts thereof in a solvent or solvent mixture being mixed in step a), optionally with the addition of solubility-increasing and/or agglomeration-suppressing additives.

In a further preferred embodiment, the processes according to the invention comprise preparing the sterile solution for step a) by

-   a) dissolving a salt or complex of a basic peptide in a solvent or     solvent mixture, -   b) adding the aliphatic or aromatic organic carboxylic acid and/or     salts thereof in solid, suspended or dissolved form with mixing to     the solution of the salt or complex of a basic peptide from step a),     and dissolving, and -   c) sterilizing the solution obtained in this way by filtration.

The sterilization of the solution or solutions in step a) generally takes place preferably by sterilizing filtration, sterilization by radioactivity such as, for example, gamma irradiation not being appropriate.

The slightly soluble peptide complex, which has been generated in step b) of the processes according to the invention, and precipitates at the latest after addition of the diluent or diluent mixture, of the basic peptide with the carboxylic acid may also be slightly soluble within the meaning of this invention in the original solvent or solvent mixture, and/or precipitates to form a suspension, even before addition of the diluent or diluent mixture.

The term “slightly soluble” relating to “basic peptide complex” means for the purposes of this invention that the solubility, i.e. the maximum amount of the salt or complex of the basic peptide which dissolves in a solvent and/or diluent or mixtures thereof under standard conditions, is equal to or less than 1000 mg/l, preferably 300 mg/l, particularly preferably 100 mg/l. The solvent or diluent or mixtures thereof employed to determine the solubility is preferably a solvent and/or diluent or mixtures thereof used for the purposes of this invention, preferably water.

Assessment and assignment of the criterion “slightly soluble” in relation to “basic peptide complex” for the purposes of this invention are decided by the solubility of the basic peptide complex after complete addition of the diluent or diluent mixture in step b) and before carrying out step c) of the process described above in the mixture, which is then present, of solvent and diluent or mixtures thereof, irrespective of whether an addition of the diluent or diluent mixture takes place in one or more steps. The solubility can easily be established by the skilled worker on the basis of his expert knowledge, e.g. by appropriate preliminary tests.

In a preferred embodiment, the processes according to the invention comprise further diluent or diluent mixture being added in one or more, preferably in more, steps with mixing in the separation process in step c).

In a further preferred embodiment, the processes according to the invention comprise employing the same diluent or diluent mixture in step b) and in step c).

Suitable as carboxylic acid according to the invention are branched or unbranched, saturated or unsaturated aliphatic organic carboxylic acids and aromatic organic carboxylic acids consisting of from 2 to 30 carbon atoms, it being possible for the latter to consist of one or more aromatic ring systems, to be fused or non-fused, to be substituted or not substituted on the aromatic ring system. Such carboxylic acids may also be polycarboxylic acids, for example di-, tri- or tetracarboxylic acids, or else sulfonic acids or phosphoric acids. Preferred for a use according to the invention is pharmaceutical and toxicological acceptability as known to the skilled worker, for example from the GRAS (“General Recognized As Safe”) list. Additionally preferred for the purposes of this invention are adipic acid, alginic acid, malic aid, ascorbic acid, benzenesulfonic acid, succinic acid, dibutyl phosphoric acid, dihexadecyl phosphoric acid, dioctyl phosphoric acid, acetic acid, fumaric acid, gluconic acid, glucuronic acid, glutamic acid, alpha-lipoic acid, maleic acid, malonic acid, lactic acid, octyl phosphoric acid, oleic acid, tartaric acid and/or salts thereof, such as, for example, ammonium salts and salts of the alkali metals and alkaline earth metals. Particularly preferred for the purposes of this invention are embonic acid, citric acid, palmitic acid, salicylic acid, tannic acid, stearic acid, benzoic acid, cinnamic acid and/or salts thereof, such as, for example, ammonium salts and salts of the alkali metals and alkaline earth metals.

In a further preferred embodiment, the aliphatic or aromatic organic carboxylic acids are selected from the group consisting of “embonic acid, citric acid, palmitic acid”.

Examples of suitable solvents and/or diluents are: water, ethanol, acetic acid, methanol, propanol, isopropanol, n-butanol, tert-butanol, acetone, or methyl ethyl ketone or a mixture of two or more of the abovementioned solvents as solvent mixture and/or diluent mixture. Solvents and diluents may be identical or different. Preferred solvents or solvent mixtures are water, ethanol, acetic acid, isopropanol, tert-butanol or acetone and mixtures thereof. Aqueous solvent mixtures, i.e. mixtures of one or more organic solvents, such as, for example, those listed above, and water with a water content of 1-90%, preferably 4-80%, are particularly preferred.

It is particularly preferred to employ as solvent mixture a water-ethanol mixture having an ethanol content of from 10 to 99% (m/m), preferably 20 to 96% (m/m), with preference 50 to 90% (m/m), in particular around 70% (m/m).

Preferred diluents are water, ethanol, acetic acid, methanol, propanol, isopropanol, n-butanol, tert-butanol, acetone or methyl ethyl ketone or mixtures of two or more of these diluents.

The particularly preferred diluent is water.

In one variant, the additives which increase the solubility and/or suppress agglomeration, in particular gel formation, and which are optionally to be added in step a) of the process for producing sterile suspensions of slightly soluble basic peptide complexes are added during the production of the joint solution or of the separate solutions before the sterilization and before carrying out process steps a) i) or a) ii).

Surfactants are preferably employed for these additives, with particular preference for surfactants selected from the group consisting of: “Tween 20 (INCI polysorbate 20, polyoxyethylene(20)sorbitan monolaureate), Tween 80 (INCI polysorbate 80, polyoxyethylene(20)sorbitan monooleate), Cremophor RH 40 (macrogol/glycerol hydroxystearate 40, INCI PEG-40 hydrogenated castor oil), Cremophor RH 60 (macrogol/glycerol hydroxystearate 60, INCI PEG-60 hydrogenated castor oil), Cremophor EL (macrogol/glycerol ricinoleate 35, poloxyl 35 castor oil) and solutol HS-15 (polyethylene glycol 15-hydroxystearate, macrogol/glycerol hydroxystearate 15)”. These and further additives are known to the skilled worker for example from “Fiedler—Lexikon der Hilfsstoffe für Pharmazie, Kosmetik und angrenzende Gebiete” (5th edition 2002).

Preparation of the Solution/Solutions for the Procedure According to Process Steps a) i) and ii) without the addition of such additives which increase the solubility and/or suppress agglomeration, in particular gel formation, is preferred.

Process steps a) to d) of the process for producing sterile suspensions of slightly soluble basic peptide complexes, and the process for producing sterile lyophilizates of slightly soluble basic peptide complexes are preferably carried out under completely aseptic conditions in the closed pharmaceutical production system familiar to the skilled worker. A production system of this type can for the purposes of this invention consist of one or more containers known to the skilled worker from his expert knowledge and suitable for aseptic pharmaceutical production. These containers may moreover have any technically possible volume. It is moreover possible for process steps a) to d) to be carried out in one and the same container or in two or more containers. In the case of two or more containers, it is also possible for two or more of the process steps to be carried out in one container. In the case of more than one container, they may also be connected together in a suitable manner known to the skilled worker but nevertheless also be separable from one another. The aseptic transfer of any materials, such as, for example, suspensions and solutions of substances and mixtures of substances, between two or more containers can likewise take place in a manner known to the skilled worker, such as, for example, through application of pressure or reduced pressure (e.g. by pumps). In addition, a protective gas, e.g. nitrogen, can be used in such a process step. Each container is additionally distinguished by being controllable to a desired specific temperature through the presence of a suitable cooling system, e.g. cooling jacket, using a suitable coolant. Cooling systems and coolants are known to the skilled worker from his expert knowledge. The temperature which can be set by the cooling system for carrying out process steps a) to d) is preferably 0-40° C., with preference 2-25° C., particularly preferably 4-16° C. In addition, each container may optionally be movable, e.g. through the presence of appropriate movable elements such as, for example, rollers, and optionally have a removable device for mixing, preferably a stirrer, for example a paddle stirrer as used in pharmaceutical production.

In a preferred embodiment, the processes according to the invention comprise carrying out process steps a) to d) in one and the same container, it being possible for the container optionally to have a removable device for mixing.

In a further preferred embodiment, the processes according to the invention comprise carrying out process steps a) to d) in two or more containers, it being possible for each container optionally to have a removable device for mixing, and it also being possible for two or more of the process steps to be carried out in one container.

The mixing in process steps a) to d) of the process according to the invention preferably takes place by stirring and can optionally be carried out continuously or at intervals. The mixing can, however, also be achieved diversely, e.g. by a plurality of mixing forms, simultaneously or sequentially, continuously or at intervals, for example by pumping in a circulatory production system and in this case with or without additional stirrers.

When carrying out the mixing, care must be taken that losses of yield are minimized, for example there is no foam formation or losses of basic peptide complex by increased deposition on the container walls, as may be caused, for example, by too vigorous and rapid stirring. However, an appropriate optimization of the mixing can easily be effected by the skilled worker on the basis of his expert knowledge.

(Adequate) mixing will for example prevent agglomeration of the particles of the slightly soluble basic peptide complex, as well as the formation of a solid sediment which cannot be resuspended, or can be only partially resuspended, and inter alia, ensures that the suspension of the slightly soluble basic peptide complex produced after process steps a) to d) is homogeneous and can be administered parenterally directly.

It is also ensured inter alia that the suspension produced by the process for producing sterile suspensions suitable for parenteral administration of slightly soluble basic peptide complexes by reconstituting the sterile lyophilizate with a sterile physiologically tolerated reconstituting medium is likewise homogeneous and shows no agglomeration of the peptide particles and/or formation of a solid sediment which is not or is only partially resuspendable, and can also be administered parenterally directly.

Generation of the suspension of the slightly soluble basic peptide complex in step b) of the process for producing sterile suspensions of slightly soluble basic peptide complexes takes place by reducing the solubility of the basic peptide complex resulting after the reaction of the basic peptide with the carboxylic acid by adding diluent or mixture of diluent in one or more steps until the slightly soluble basic peptide complex precipitates. To achieve a maximally complete, quantitative precipitation and minimization of losses of yield, it is necessary for there to be careful selection and optimization of the solvent and diluent used, or mixtures thereof, but also of the temperature. However, such selection and optimization experiments are known to the skilled worker from his expert knowledge and are simple to carry out, such as, for example, solubility determinations in the particular medium at, for example, various temperatures or visual observation of the onset of suspension.

The continuous or stepwise separation process in step c) of the process for producing sterile suspensions of slightly soluble basic peptide complexes is distinguished according to the invention by depletion of solvent or solvent mixture, of free non-peptide ions, of excess carboxylic acid and of the additives which are optionally added to increase the solubility and/or suppress agglomeration in the suspension obtained in step b), with the liquid content of the suspension being reduced and optionally further diluent or diluent being added in one or more steps. The intention of the depletion is in particular to reduce the content of solvent or solvent mixture and of additives which are optionally added to increase the solubility and/or suppress agglomeration, in particular gel formation, to an extent enabling lyophilization of the suspension of the slightly soluble basic peptide complex but also permitting direct parenteral administration of the suspension or of the reconstituted lyophilizate of the slightly soluble basic peptide complex.

The extent of the solvent content with which freeze drying is still permitted depends on the particular solvent or solvent mixture. Characteristic limits are known to the skilled worker from the relevant specialist literature. For example, the review by Teagarden and Baker (European Journal of Pharmaceutical Sciences, 2002, 15: 115-133) indicates various solvents or solvent mixtures (cosolvent systems) and values for their contents with and/or at which a freeze drying of various pharmaceutical preparations took place. Thus, inter alia, the advantages of a 20% (v/v) tert-butanol/water solvent mixture are discussed, but at the same time it is also stated that with other solvent mixtures, such as, for example, ethanol/water, n-propanol/water or methanol/water, the content of the particular organic solvent appears to be limited to a maximum of ten percent by volume for complete successful lyophilization.

The extent of the additives which increase the solubility and/or suppress agglomeration, in particular gel formation, such as, for example, surfactants, preferably Tween 20 (INCI polysorbate 20, polyoxyethylene(20)sorbitan mono-laureate), Tween 80 (INCI polysorbate 80, polyoxyethylene(20)sorbitan monooleate), Cremophor RH 40 (macrogol/glycerol hydroxystearate 40, INCI PEG-40 hydrogenated castor oil), Cremophor RH 60 (macrogol/glycerol hydroxystearate 60, INCI PEG-60 hydrogenated castor oil), Cremophor EL (macrogol/glycerol ricinoleate 35, poloxyl 35 castor oil) and solutol HS-15 (polyethylene glycol 15-hydroxystearate, macrogol/glycerol hydroxystearate 15), which still permits direct parenteral administration of the suspension or of the reconstituted lyophilizate of the slightly soluble basic peptide complex depends on the particular peptide complex and on the particular pharmaceutical formulation, but is known to the skilled worker on the basis of his expert knowledge. Thus, for example, numerous pharmaceutical additives which increase the solubility for various oral and parenteral formulations, and values for their contents, are discussed in the review by Strickley (Pharmaceutical Research, 2004, 31:201-230).

A depletion in the separation process of step c) can take place according to the invention in two ways, by use of a filter or by centrifugation, and can take place in one or more steps. This may optionally entail addition of further diluent or diluent mixture in one or more steps, although further addition is preferred. In addition, the concentration of the suspension of the slightly soluble basic peptide complex can, after the depletion has taken place, be adjusted by specific addition of the diluent or diluent mixture and be higher than, the same as or lower than the initial concentration before depletion. Increasing the concentration of the suspension is preferred.

In the depletion by use of a filter, on the basis of the screen size and/or of the retention range of the filter the liquid content of the suspension, the content of solvent or solvent mixture, of free non-peptide ions, of excess carboxylic acid and of the additives which are optionally added to increase the solubility and/or suppress agglomeration is reduced, but the particles of the slightly soluble basic peptide complex are retained. In this case, in particular the content of the solvent or solvent mixture and, where appropriate, also of the additives which increase the solubility and/or suppress agglomeration, in particular gel formation, is reduced by the diluting effect of the diluent or diluent mixture which is preferably added to the particular extent which is known to the skilled worker and is desired.

The term “filter” includes according to the invention all materials suitable for the depletion in process step c), these being chemically inert towards the solvent and diluent or mixtures thereof and having a porous and/or sieve-like structure which makes it possible to retain the particles of the suspension of the slightly soluble basic peptide complex and to deplete the liquid content of the suspension.

Filters for the purposes of this invention may be for example paper filters, glass fiber filters, quartz fiber filters, depth-type filters, membranes, membrane filters, gauzes and filter gauzes. Preference is given to membranes, membrane filters, gauzes and filter gauzes. Examples of suitable materials are: cotton, cellulose, cellulose, cellulose mixed esters, cellulose nitrate, cellulose acetate, regenerated cellulose, glass fibers, quartz microfibers, glass, borosilicate glass, borosilicate glass fibers, plastic, polymer, polyamide, polycarbonate, polypropylene, PTFE (Teflon), PVDF, metals, metal alloys, coated metals, sintered metals, ceramics. Preference is given to glass, ceramics, metals such as, for example, iron, nickel and chromium, metal alloys, such as, for example, stainless steel and brass, and coated metals and/or metal alloys such as, for example, teflonized stainless steel. Stainless steel is particularly preferred. Further preferred materials are plastic, polymer, polyamide, polycarbonate, polypropylene, PTFE (Teflon), PVDF, polysulfone and/or mixtures thereof.

By plastics are meant all known materials whose basic constituent are synthetically or semisynthetically generated polymers. Technical properties of plastics, such as moldability, hardness, elasticity, fracture resistance, thermal and chemical stability can be varied within wide limits through the selection of the starting material, the production process and the admixture of additives. Such molding compositions provided with additives are then characterized according to DIN EN ISO 1043 (thermoplastics) and according to DIN 7708 (thermosets). Semisynthetic plastics are produced by processing natural polymers (for example cellulose to celluloid). Synthetic plastics are generated by polymerization (polyaddition, polycondensation etc.) from a monomer. All such plastics and polymers are to be regarded as belonging to the invention.

Also preferred for the purposes of this invention are three-dimensional filters, i.e. filters whose separation surface extends into three-dimensional space, such as, for example, a gauze or filter gauze made of, for example, stainless steel, e.g. in the form of a cylinder which is open at the top and bottom (filter drum). Such three-dimensional filters may, because of their greatly enlarged surface area, lead to an improved separation in the separation process, it being possible for such an improvement to be manifested by one or more advantageous parameters, for example by a time-saving separation process, use of less starting material, greater yield of product, a product having improved properties, etc.

Thus, for example, use of a stainless steel gauze filter drum leads to a time saving by a factor of 2 to 3 when carrying out the separation process. Likewise, the use of one or more hollow fiber membranes made of, for example, PVDF and/or polysulfone leads to a considerable time saving.

The selection of the screen size and/or of the retention range of the filter in this connection depends on the particle size distribution of the particles of the particular slightly soluble basic peptide complex. The particle size distribution varies for each individual peptide complex and can easily be determined by the skilled worker with the aid of his expert knowledge, e.g. by laser diffraction/laser diffractometry. The screen size and/or the retention range of the filter is to be chosen in this connection so that, on the one hand, the particles of the slightly soluble basic peptide complex are retained as completely as possible, and thus losses of yield are minimized, but, on the other hand, the filter does not become blocked and depletion of the liquid content of the suspension is impeded or, for example owing to an exorbitantly large expenditure of time and/or pressure to be applied, is not or scarcely technically feasible. The selection is a simple matter for the skilled worker on the basis of his expert knowledge and, for example, by means of appropriate optimization experiments.

The terms “screen size” and “retention range” in relation to filters include according to the invention both nominal values, i.e. for example values stated by the manufacturer or on the basis of conventional standardization, natural values established by suitable measurement methods, also averages in the case of size ranges, such as, for example, the average screen size. Preference is given for the purposes of this invention to a screen size and/or a retention range of 1-250 μm, preferably of 2-100 μm, particularly preferably of 3-30 μm. Preference is further given for the purposes of this invention to a screen size and/or a retention range of 0.1-250 μm, preferably of 0.1-100 μm and particularly preferably of 0.1-30 μm.

In a preferred embodiment, the processes according to the invention comprise employing as filter a stainless steel gauze with a retention range of 1-250 μm, preferably of 2-100 μm and particularly preferably of 3-30 μm, it also being possible for the stainless steel gauze to be a three-dimensional filter drum.

In a further preferred embodiment, the processes according to the invention comprise the filter being selected from the group consisting of: “membrane, membrane filter” and is preferably one or more hollow fiber membranes made of materials selected from the group consisting of: “plastic, polymer, polyamide, polycarbonate, polypropylene, PTFE, PVDF, polysulfone” and preferably consists of PVDF and/or polysulfone, and is employed with a screen size and/or retention range of 0.1-250 μm, preferably of 0.1-100 μm and particularly preferably of 0.1-30 μm.

In the separation process by use of a filter, the device for mixing, preferably a stirrer, is disposed in the corresponding container just above the filter so that adequate mixing is achieved, the filter is not damaged and/or its functioning impaired during the mixing, and blocking of the filter, as described above, is prevented. A corresponding optimization is a simple matter for the skilled worker. This must also be taken into account on use of a three-dimensional filter, and in such a case the device for mixing preferably extends into three-dimensional space, e.g. a three-dimensional rod stirrer on use of a stainless steel gauze filter drum. In addition, mixing by pumps is preferred in the separation process after step c), and optionally in addition by an optionally removable device for mixing, this device preferably representing a stirrer.

Depletion of the liquid content of the suspension by use of a filter can optionally take place with application of pressure. It is possible in this connection for the application of pressure to take place for example continuously or at intervals and rising or falling. Care must be taken on application of pressure that the filter does not become blocked and depletion impeded or, for example owing to an exorbitantly large expenditure of time, is not or scarcely technically feasible. The way of applying pressure in aseptic pharmaceutical production is known to the skilled worker from his expert knowledge and can take place for example through sterile-filtered compressed air or sterile-filtered nitrogen, if necessary using compression aids such as, for example, a compressor. Corresponding devices are attached to the container or containers. Application of pressure in the range from 0 to 2 bar is preferred for the purposes of the invention.

On depletion by centrifugation, the liquid content of the suspension, the content of solvent or solvent mixture, of free non-peptide ions, of excess carboxylic acid and of the additives which are optionally added to increase the solubility and/or suppress agglomeration is reduced by the centrifugation in one or more steps to obtain the suspension of the slightly soluble basic peptide complex. This entails in particular reduction of the content of the solvent or solvent mixture and, where appropriate, of the additives which increase the solubility and/or suppress agglomeration, in particular gel formation, by the diluting effect of the diluent or diluent mixture which is preferably added to the particular extent which is known to the skilled worker and desired.

The centrifugation can optionally take place horizontally or vertically. Sedimentation of the particles of the slightly soluble basic peptide complex takes place horizontally, i.e. perpendicular to the vertical rotation axis, on horizontal centrifugation (vertical rotation axis), and vertically, i.e. perpendicular to the horizontal rotation axis, on vertical centrifugation (horizontal rotation axis). The terms “horizontal” and “vertical” in connection with centrifuges, types of centrifuges, rotors and types of rotors relate, in contrast thereto, to the particular rotation axis and not to the centrifugation and direction of sedimentation of the particles.

Centrifuges which can be used for the purposes of this invention are all types of centrifuge known to the skilled worker, in use in pharmaceutical production and suitable for aseptic production, preferred examples being horizontal centrifuges, vertical centrifuges, horizontal peeler centrifuges, vertical peeler centrifuges and pusher centrifuges. The term “centrifuge” also includes in this connection all accessories which are known to the skilled worker and characterize a centrifuge, such as, for example, rotors and centrifugation containers or inserts, but also additional internals as detailed hereinafter. All known types of rotor can be employed as rotor, e.g. preferably vertical and horizontal rotors, swing-out rotors and fixed-angle rotors, it being possible for the rotors to be equipped with one or more centrifugation containers as insert, which may optionally be removable or a fixed component of the particular rotor. In the case of more than one centrifugation container, these may be inclined in relation to the rotation axis in the particular rotor, with a preferred inclination of from 0° to 90°.

Preferred centrifugation for the purposes of this invention is horizontal centrifugation (vertical rotation axis). Preference is further given according to the invention to a centrifugation container as optionally removable or fixed component of a vertical rotor with an inclination of 0° to the vertical rotation axis. Also preferred are two or more centrifugation containers as optionally removable or fixed component of a vertical rotor with an inclination of from 0° to 90° to the vertical rotation axis.

The centrifuges consist of materials known to the skilled worker from his expert knowledge and suitable for aseptic pharmaceutical production, such as, for example, stainless steel, and may advantageously be additionally prepared for the production in order for example to assist in preventing agglomeration of the particles of the slightly soluble basic peptide complex and/or formation of a solid sediment, such as, for example, centrifugation containers of ground stainless steel with a sliding behavior of the particles to be centrifuged which is improved by the depth and alignment of the grinding.

The centrifuges may moreover have additional internals known to the skilled worker, preferably devices for mixing, such as, for example, a stirrer, for adding solvent and/or diluent and/or suitable pharmaceutical excipients, carriers and/or bulking agents, such as, for example, a filling pipe, for reducing the liquid content of the suspension, such as, for example, a suction pipe, mechanical and/or pneumatic peeler devices. It is moreover possible for a plurality of such additional internals and/or functions thereof also to be combined in one device, such as, for example, a paddle stirrer which is hollow inside and serves simultaneously also as filling pipe and/or suction pipe. Such additional internals may be optionally removable or a fixed component of the centrifuge. The operation and/or actuation of such additional internals is known to the skilled worker and, in the case of the device for mixing, such as, for example, a stirrer, can take place for example from outside through use of magnets.

The centrifugation speed or relative centrifugal force (RCF) can assume all the conventional values known to the skilled worker, for example 1-100 000 g or corresponding revolutions per minute. The centrifugation speed or relative centrifugal force is to be chosen in this connection so that the agglomeration of the particles of the slightly soluble basic peptide complex, and the formation of a solid sediment which is not or is only partially resuspendable is prevented. A suitable centrifugation speed or relative centrifugal force or ranges thereof can easily be determined by the skilled worker with the aid of his expert knowledge, e.g. by appropriate preliminary experiments.

Reduction of the liquid content of the suspension can optionally take place during the centrifugation or thereafter in one or more steps and, for example, by use of a suction pipe. It is preferred for the purposes of this invention to carry out the centrifugation at intervals, with the reduction in the liquid content of the suspension taking place in the pauses between the centrifugation steps and/or after the centrifugation, and ensuring during this that the suspension of the slightly soluble basic peptide complex is retained, i.e. for example not all the liquid content is removed, and losses of yield through, for example, too extensive, rapid or imprecise removal of the supernatant, are minimized.

The preferred addition of the diluent or diluent mixture can optionally take place during the centrifugation, after the centrifugation and/or, if the centrifugation is carried out at intervals, also in the pauses between the centrifugation steps in one or more steps, but preferably in the pauses between the centrifugation steps and/or after the centrifugation after the respective reduction of the liquid content of the suspension.

The mixing during the separation by centrifugation can optionally be carried out continuously or at intervals. Preference is given to mixing by stirring at intervals, such as, for example, in the pauses between the centrifugation steps and after the centrifugation, after the reduction of the liquid content of the suspension, and during and/or after the addition, taking place after this reduction, of the diluent or diluent mixture. Additionally preferred for the purposes of this invention is a mixing which is brought about solely by acceleration and braking of the centrifugation container(s) during the centrifugation, optionally with the assistance of an additional device for mixing.

The device for mixing is disposed so that adequate mixing of the suspension of the slightly soluble basic peptide complex is ensured. Further additional internals such as, for example, to reduce the liquid content of the suspension, such as, for example, suction pipe, but also combined appliances described above with, for example, a mixing and removal function, are to be disposed and/or designed so that losses of yield through, for example, too extensive, rapid or imprecise removal of the supernatant are minimized. The dispositions suitable in each case can easily be established by the skilled worker through appropriate experiments.

In step d) of the process according to the invention it is possible optionally to add to the suspension or the lyophilizate suitable pharmaceutical excipients, carriers and/or bulking agents such as, for example, mannitol, sorbitol, xylitol, trehalose, glucose, soluble starch, sucrose and saccharose. Addition of these excipients, carriers and/or bulking agents can take place as sterile solid and/or as sterile solution.

Preference is given for the purposes of this invention to addition of mannitol, sorbitol, xylitol, trehalose, glucose, soluble starch, sucrose and/or saccharose as sterile solution in step d) of the process for producing sterile suspensions of slightly soluble basic peptide complexes, with the mixing preferably taking place by stirring. Preference is further given to the addition of mannitol, sorbitol, xylitol, trehalose, glucose, soluble starch, sucrose and/or saccharose as sterile solid in the process for producing sterile lyophilizates of slightly soluble basic peptide complexes, it being possible for the addition to take place before, during and/or after the lyophilization and optionally with mixing.

In a preferred embodiment, the process for producing sterile suspensions comprises

-   a) mixing a sterile solution comprising the acetate salt of an LHRH     antagonist selected from the group consisting of: “cetrorelix,     teverelix, ozarelix (D-63153)” and the salt of a carboxylic acid     selected from the group consisting of: “embonic acid, citric acid,     palmitic acid” in an aqueous ethanolic solvent mixture having an     ethanol content of from 50 to 90% (m/m), in particular around 70%     (m/m), -   b) generating, by mixing and addition of water as diluent in one or     more steps, a suspension of the slightly soluble basic peptide     complex of the basic peptide with the carboxylic acid, where the     molar ratio of basic peptide to carboxylic acid in the slightly     soluble basic peptide complex assumes a value of between 2:1 and     1:2, -   c) depleting, while mixing and with further addition of water as     further diluent in one or more steps and optionally with application     of pressure, ethanol, free non-peptide ions and excess carboxylic     acid in the suspension obtained in step b) through use of a     stainless steel gauze filter having a retention range of 2-100 μm,     preferably of 3-30 μm, and reducing the liquid content of the     suspension, and -   d) adding, while mixing the sterile suspension, thus obtained, of     the slightly soluble basic peptide complex, a mannitol as bulking     agent-containing (sterile) solution,     where process steps a) to d) are carried out in one and the same or     two containers, and the mixing is brought about by a suitable     stirrer.

In a further preferred embodiment, the process for producing sterile suspensions comprises employing as filter in step c) one or more hollow fiber membranes which preferably consist of PVDF and/or polysulfone and have a screen size and/or retention range of 0.1-100 μm, preferably of 0.1-30 μm, in particular 0.2 μm, and the mixing being brought about by pumps and optionally additionally by an optionally removable device for mixing, this device preferably representing a stirrer.

In a further preferred embodiment, the process for producing sterile lyophilizates comprises lyophilizing the sterile suspension obtained in step d) of the process for producing sterile suspensions according to the preferred embodiments described above.

In a further preferred embodiment, the process for producing sterile suspensions suitable for parenteral administration comprises reconstituting with water for injections the lyophilizate obtained by the preferred embodiment described above of the process for producing sterile lyophilizates.

In the process for producing sterile lyophilizates of slightly soluble basic peptide complexes, the sterile suspension of the slightly soluble basic peptide complex which is obtained in steps c) or d) of the process for producing sterile suspensions of slightly soluble basic peptide complexes can be lyophilized and optionally pharmaceutical excipients, carriers and/or bulking agents be added. Lyophilization of the sterile suspension of the slightly soluble basic peptide complex with optional addition of the suitable pharmaceutical excipients, carriers and/or bulking agents takes place in a way known to the skilled worker from his expert knowledge with the assistance of a standard freeze-drying system which is suitable for aseptic pharmaceutical production. The dispensing of the suspension, which is necessary before the lyophilization, into suitable vials is likewise known to the skilled worker and takes place using a standard dispensing system which is suitable for aseptic pharmaceutical production which is to be understood according to the invention as also being container and component of the closed production system.

In the process for producing sterile suspensions, suitable for parenteral administration, of slightly soluble basic peptide complexes, the sterile lyophilizate of the slightly soluble basic peptide complex which has been obtained by the process for producing sterile lyophilizates of slightly soluble basic peptide complexes can be reconstituted with a sterile physiologically tolerated reconstituting medium. Such reconstituting media are known to the skilled worker. The reconstituting media used for the purposes of this invention are preferably to be only those which contain no additives which increase the viscosity and/or otherwise increase the stability of the suspension and/or induce allergic reactions, but especially no carboxymethylcellulose (CMC). The preferred reconstituting medium is sterile water, particularly preferably water for injections.

The sterile suspensions produced according to the invention by the process described above for producing sterile suspensions of slightly soluble basic peptide complexes, but also the process for producing sterile suspensions of slightly soluble basic peptide complexes suitable for parenteral administration are surprisingly distinguished inter alia by remaining stable over a period of at least 2 hours, preferably 4, 8, 12, 24, 36, 48 and/or 72 hours, but usually also for several days and weeks, and without requiring the addition of additives which increase the viscosity and/or otherwise increase the stability of the suspension, for example carboxymethylcellulose (CMC) which, in some circumstances, may also induce allergic reactions.

The terms “stable” and “stability” in relation to the suspension of the slightly soluble basic peptide complex mean according to the invention that no visually recognizable separation of the suspension into mutually separate solid and liquid phases (physical stability) takes place during the stability period and without mixing; on the contrary, the suspension remains homogeneous. In addition, the terms “stable” and “stability” mean in this connection that neither the peptide component of the basic peptide complex nor the carboxylic acid component undergoes chemical decomposition (chemical stability).

Assessment and assignment of the criteria “stable” and “stability” in relation to the suspension of the slightly soluble basic peptide complex is a simple matter for the skilled worker on the basis of his expert knowledge. Thus, the start of separation can be determined for example visually through the start of sediment formation and/or through the occurrence of homogeneity, i.e. regions of visually detectable differences in particle density. Chemical stability can be demonstrated by suitable chromatographic methods, for example by HPLC.

In addition, sterile suspensions produced according to the invention by the processes described above for producing sterile suspensions of slightly soluble basic peptide complexes and processes for producing sterile suspensions, suitable for parenteral administration, of slightly soluble basic peptide complexes are surprisingly distinguished by their particles having a more advantageous morphology, for example surface area, form, shape, size and/or specific density.

The morphology of the particles can for the purposes of this invention surprisingly and advantageously be controlled in a targeted manner by suitable variations of the conditions for the generation of the suspensions by adding the diluent or diluent mixture, for example by the speed of mixing, speed of addition, temperature, nature of the mixing device (e.g. type of stirrer), mixing time, ratio of basic peptide to carboxylic acid etc. Such a targeted possibility for control is a substantial advantage of the processes according to the invention compared with the processes described in the prior art and leads to advantageous effects, e.g. those described herein, of the suspensions according to the invention. The skilled worker can easily optimize the process conditions for such a targeted control for the purposes of this invention on the basis of his expert knowledge, for example by carrying out appropriate experimental preliminary tests.

It has also been found, surprisingly, that a change in the morphology of the particles influences the release of the basic peptide (active ingredient) from the administered suspension of the slightly soluble basic peptide complex, for example through the presumably different formation of a more or less dense gel network, from which the active ingredient is dissolved at different rates.

The sterile suspensions produced according to the invention by the processes described above for producing sterile suspensions of slightly soluble basic peptide complexes and processes for producing sterile suspensions of slightly soluble basic peptide complexes suitable for parenteral administration is also surprisingly distinguished by the particles of the slightly soluble basic peptide complex which have sedimented not agglomerating and not forming any sediment which is not or is only partially resuspendable, and by a stable suspension being obtained again by simple mixing, such as, for example, brief shaking or stirring, certainly even after several weeks and months.

In addition, the sterile suspension produced according to the invention by the process for producing sterile suspensions of slightly soluble basic peptide complexes, and the sterile suspensions produced by the process for producing sterile suspensions, suitable for parenteral administration, of slightly soluble basic peptide complexes are surprisingly distinguished by being amenable to direct parenteral administration, i.e. not requiring further processing or treatment for parenteral administration, and being amenable to administration without further additions such as, for example, additives which increase the viscosity and/or otherwise increase the stability of the suspension and in particular without carboxymethylcellulose (CMC).

The sterile suspensions produced according to the invention are further surprisingly distinguished by showing improved active ingredient release (drug release), it being possible for this improvement to represent both an increase in the absolute amount of cumulatively released basic peptide such as, for example, cetrorelix, and to be an improved controlled release, for example a release of basic peptide which is continuously increased and/or more uniform over a particular period, or else a prolongation of the period of active ingredient release. Thus, an improved controlled release of the sterile suspensions produced according to the invention may be characterized for example by a fast release of the carboxylic acid component from the basic peptide complex, whereas the peptide component (the active ingredient) is advantageously delivered from the complex in a controlled manner over a prolonged period.

The sterile suspensions produced according to the invention by the process for producing sterile suspensions of slightly soluble basic peptide complexes and processes for producing sterile suspensions, suitable for parenteral administration, of slightly soluble basic peptide complexes are additionally surprisingly distinguished by showing an improved local tolerability on subcutaneous parenteral administration.

In addition, the suspensions produced according to the invention surprisingly show a more advantageous hormone suppression. Thus, for example, in the treatment of endometriosis or uterine myomas in women, a reliable, therapeutically effective and controlled reduction in the estradiol level is achieved without chemical castration being brought about and hormone withdrawal manifestation which are disadvantageous for the patients recurring. In the treatment of benign prostate hyperplasia (BPH) in men, for example, a pronounced, deeper and longer-lasting reduction in the testosterone level is achieved, but likewise without reaching the castration level and/or causing disadvantageous hormone withdrawal manifestations.

The sterile lyophilizate of the slightly soluble basic peptide complex obtained by the process for producing sterile lyophilizates of slightly soluble basic peptide complexes is surprisingly distinguished by being directly reconstitutable without further processing or treatment with a sterile physiologically tolerated reconstituting medium, and the resulting sterile suspension being amenable to direct parenteral administration.

The sterile suspensions produced according to the invention, and the sterile lyophilizate may also be component of pharmaceutical formulations for parenteral administration, these comprising at least one sterile suspension, produced according to the invention, of a slightly soluble basic peptide complex or at least one sterile lyophilizate of a slightly soluble basic peptide complex.

In addition, the sterile lyophilizates produced according to the invention may also be component of a kit which includes at least one sterile lyophilizate of a slightly soluble basic peptide complex and at least one sterile physiologically tolerated reconstituting medium.

The sterile suspensions and sterile lyophilizates, produced according to the invention, of slightly soluble basic peptide complexes, and the pharmaceutical formulations for parenteral administration can be used as medicaments for the treatment and prophylaxis of diseases and pathological states in mammals, especially in humans.

They are preferably used for the treatment of benign or malignant neoplastic diseases, in male fertility control, in hormone therapy, hormone-dependent neoplastic diseases, female sub- or infertility, for in vitro fertilization, for female contraception, for the treatment of HIV infections, for the treatment of neurological or neurodegenerative disorders, and for protection from side effects due to chemotherapy, and particularly preferably for the treatment of prostate cancer, benign prostate hyperplasia (BPH), endometriosis, uterine fibroids, uterine myomas, breast cancer, premenopausal breast cancer, uterine cancer, endometrial cancer, cervical cancer, ovarian cancer, precocions puberty, hirsutism, polycystic ovary syndrome, AIDS, ARC (AIDS related complex), Karposi sarcoma, tumors originating from the brain and/or nervous system and/or meninges (see WO 99/01764), dementia and Alzheimer's.

BRIEF DESCRIPTION OF THE DRAWINGS

These show:

FIG. 1: A longitudinal section through a closed production system according to the invention for depletion by means of filter separation.

FIG. 2: A longitudinal section through a production system according to the invention for depletion by means of centrifugation.

FIG. 3: A longitudinal section through a closed production system according to the invention for depletion by means of three-dimensional filter separation.

FIG. 4: A diagrammatic representation of a closed production system according to the invention for depletion by means of hollow fiber membrane filter separation.

DESCRIPTION OF THE PREFERRED DESIGN OF APPARATUS

FIG. 1 depicts a longitudinal section through a container 1 which is employed to produce the sterile suspensions of slightly soluble basic peptide complexes. As is evident in FIG. 1, the container 1 is used to react the starting materials dissolved in the sterile solution after step a) i) or the sterile solutions after step a) ii) of the process. The container 1 is surrounded by a cooling system 2 a, 2 b to adjust and maintain the reaction temperature, with provision of an entry 2 a and exit 2 b for the cooling medium. Mixing of the reaction components with further solvents or diluents and additives in process steps a) to d) takes place with a stirrer 3. The depletion of solvent or solvent mixture, ions, excess carboxylic acid and additives from the suspension of the slightly soluble basic peptide complex obtained from the reaction can be achieved with a filter 4. The stirrer 3 is disposed just above the filter 4. The apertures disposed in the upper region of the container 1 serve as charging aperture 5 or for applying pressure 6. If the depletion is carried out by means of a filter 4, the resulting suspension is discharged through a suspension outlet 7 and the reduced liquid content of the suspension is discharged through a liquid outlet 8. An element which is disposed on the container 1 and has a hinge 10 serves to open the lower part of the apparatus. The container is fixed in a frame with rollers 11 for mobile use of the apparatus.

In an embodiment depicted in FIG. 2 it is possible to dispense with use of a filter 4 if the depletion of solvent or solvent mixture, ions, excess carboxylic acid and additives from the resulting suspension of the slightly soluble basic peptide complex takes place by centrifugation.

FIG. 2 shows a longitudinal section through a centrifugation system in a design with vertical rotor axis 12 and resting on a fastening 13 of the rotor. The container 1 of a closed production system is rotatably mounted inside a cooling system 2 a, 2 b. The cooling system 2 a, 2 b is disposed outside the container 1. In this case, the container 1 is subjected to centrifugation. In this embodiment, the stirrer 3 is disposed above the base of the container. Besides the charging aperture 5, a suction pipe 9 is disposed to draw off the liquid phase and may be optionally removable or a fixed installation.

FIG. 3 depicts a longitudinal section through a container 1 which is employed to produce the sterile suspensions of slightly soluble basic peptide complexes by means of three-dimensional filter separation. As is evident from FIG. 3, the container 1 is used for reacting the starting materials dissolved in the sterile solution after step a) i) or the sterile solutions after step a) ii) of the process. The container 1 is surrounded by a cooling system 2 a, 2 b to adjust and maintain the reaction temperature, where there is provision of an entry 2 a and exit 2 b for the cooling medium. Mixing of the reaction components with further solvents or diluents and additives in process steps a) to d) takes place with a stirrer 3, this stirrer advantageously being a three-dimensional rod stirrer. The depletion of solvent or solvent mixture, ions, excess carboxylic acid and additives from the suspension of the slightly soluble basic peptide complex obtained from the reaction can be achieved with a three-dimensional filter 4 (preferably filter drum). The apertures disposed in the upper region of the container 1 serve as charging aperture 5 or for applying pressure 6. If the depletion is carried out by means of a filter 4, the resulting suspension is discharged through a suspension outlet 7 and the reduced liquid content of the suspension is discharged through a liquid outlet 8. Elements disposed on the container 1 and having a hinge 10 are used to open the apparatus.

In an embodiment depicted in FIG. 4 by means of hollow fiber membrane filter separation it is possible to dispense with the use of a filter in the initial container 1 if the depletion of solvent or solvent mixture, ions, excess carboxylic acid and additives from the resulting suspension of the slightly soluble basic peptide complex takes place in a separate hollow fiber membrane filter module 4. FIG. 4 shows a diagrammatic representation of a closed production system according to the invention for depletion by means of hollow fiber membrane filter separation. The container 1 is used to react the starting materials dissolved in the sterile solution after step a) i) or the sterile solutions after step a) ii) of the process. The container 1 is surrounded by a cooling system 2 a, 2 b to adjust and maintain the reaction temperature, with provision of an entry 2 a and exit 2 b for the cooling medium. Mixing of the reaction components with further solvents or diluents and additives in process steps a) to d) takes place by pumping through the closed production system by means of pump 14 and optionally additionally by a stirrer 3 optionally located in the container 1. The depletion of solvent or solvent mixture, ions, excess carboxylic acid and additives from the suspension of the slightly soluble basic peptide complex obtained from the reaction can be achieved with a hollow fiber membrane filtration module 4. The apertures disposed in the upper region of the container 1 serve as charging aperture 5 or for applying pressure 6. If the depletion is carried out by means of a hollow fiber membrane filter module 4, the resulting suspension is discharged through a suspension outlet 7 and the reduced liquid content of the suspension is discharged through exit from the hollow fiber membrane filter module (8).

FIG. 5: Particle size distribution of the particles of a suspension of cetrorelix embonate (2:1)

FIG. 5 shows the particle size distribution of the particles of a suspension of cetrorelix embonate which was produced as in Example 1 and measured as in Example 10. The percentage content of the particles (% by volume) is depicted as cumulative plot as a function of the particle diameter in μm.

FIG. 6: In vitro active ingredient release from various cetrorelix embonate formulations

FIG. 6 depicts the active ingredient release from various cetrorelix embonate formulations in physiological Ringer's solution according to the in vitro release carried out in Example 12. The respective cumulative amount of cetrorelix released in mg (“cetrorelix (mg) released cumulated”) is shown as a function of the time in hours (“time (h)”). The following formulations (in each case independent duplicates) were used: (i) P85P002A (suspension according to the invention), (ii) DJ5 [cetrorelix embonate (1:1.6) microparticle formulation according to DE 43 42 092 and Felberbaum et al. (1998)], (iii) 9612-002/05-g (suspension obtained according to DE 100 40 700).

FIG. 7: Comparison of testosterone suppression

FIG. 7 shows the testosterone suppression as found in Example 13. The levels are depicted normalized to the respective initial levels at the time of administration (% of baseline) (week 0=100%) and indicated for weeks 0, 1 and 2 [time (weeks)] (study 3107: suspension produced and administered according to DE 100 40 700; study JAP: suspension produced and administered according to the invention).

The contents of all cited references and patents are hereby incorporated by reference. The invention is explained in more detail by means of the following examples without, however, being restricted thereto.

EXAMPLES Example 1 Production of a Sterile Suspension of Cetrorelix Embonate (2:1) and of a Sterile Lyophilizate of 30 mg of Cetrorelix Embonate Using the Separation Process by Means of a Filter

123.7 g of cetrorelix acetate were added stepwise with continuous stirring to 3182 g of water for injection in a suitable vessel and dissolved. 10270 g of 96% (v/v) ethanol were then added with stirring. The ethanol content was subsequently adjusted to 70% (m/m) with water for injections. 17.0 g of disodium embonate were then added with continuous stirring until the disodium embonate had completely dissolved (=solution 1). 12963 g of solution 1 were subsequently transferred with the aid of a sterilizing filter (0.22 μm) into a container (see FIG. 1). The container was cooled to a temperature of 11±3° C. and kept at this temperature throughout the process. About 26544 g of precooled water for injections (11±3° C.) were then filtered sterile into the container while stirring, and a suspension of cetrorelix embonate was produced (=suspension 1). Suspension 1 was stirred for 20-30 min after addition. The sterile outlet valve (see FIG. 1, liquid outlet 8) was subsequently opened, and the suspension was concentrated through the stainless steel gauze (nominal pore size: 5 μm), employed, initially without pressure and later by applying a low pressure (<0.2 bar). After about 22580 g of clear filtrate had been discharged, the valve was closed. Thereafter, about 13737 g of precooled water for injections (11±3° C.) were again filtered sterile into the container while stirring (=suspension 2). Suspension 2 was filtered for 20-30 minutes after addition. The sterile outlet valve was then opened again, and the suspension was concentrated as described previously. After about 13910 g of clear filtrate had been discharged, the outlet valve was closed and about 7686 g of precooled water for injections (11±3° C.) were again filtered sterile into the container with stirring (=suspension 3). The suspension was stirred for 20-30 min after addition. The sterile outlet valve was then again opened, and the suspension was concentrated as described previously. After about 15110 g of clear filtrate had been discharged, the outlet valve was closed. 8280 g of this suspension were then transferred from the first container into a further sterile container and then 8310 g of a 4% (m/m) mannitol solution were filtered sterile into the further container while stirring (=suspension 4). Addition was followed by stirring for 10-15 min, and then the final suspension 4 was dispensed through the suspension outlet valve (see, for example, FIG. 1, suspension outlet 7) into 10R glass vials. The dispensing solution contains not more than 10% ethanol. The molar ratio of cetrorelix to embonate was 2:1. The filled vials (about 3000) were placed in the lyophilizer, frozen at about −45° C. and lyophilized in vacuo at a plate temperature rising from −45° C. to +20° C. in the primary drying and at about 25° C. in the secondary drying. The freeze-drying system was then flushed with sterile nitrogen, and the vials were closed with suitable stoppers in the system and then crimp-capped. The lyophilizate was reconstituted by using 2 ml of water for injections per vial. The suspension obtained by gentle swirling can be administered s.c. or i.m.

Example 2 Production of a Sterile Suspension of Teverelix Embonate (2:1) and of a Sterile Lyophilizate of 30 mg of Teverelix Embonate Using the Separation Process by Means of a Filter

115.3 g of teverelix acetate are added stepwise with continuous stirring to 3006 g of water for injection in a suitable vessel and dissolved. 9827 g of 96% (v/v) ethanol are then added with stirring. The ethanol content is subsequently adjusted to 70% (m/m) with water for injections. 15.7 g of disodium embonate are then added with continuous stirring until the disodium embonate had completely dissolved (=solution 1). 11802 g of solution 1 are subsequently transferred with the aid of a sterilizing filter (0.22 μm) into a container (see FIG. 1). The container is cooled to a temperature of 11±3° C. and kept at this temperature throughout the process. About 24203 g of precooled water for injections (11±3° C.) are then filtered sterile into the container while stirring, and a suspension of teverelix embonate was produced (=suspension 1). Suspension 1 is stirred for 20-30 min after addition. The sterile outlet valve (see FIG. 1, liquid outlet 8) is subsequently opened, and the suspension is concentrated through the stainless steel gauze (nominal pore size: 5 μm), employed, initially without pressure and later by applying a low pressure (<0.2 bar). After about 18987 g of clear filtrate have been discharged, the valve is closed. Thereafter, about 11000 g of precooled water for injections (11±3° C.) are again filtered sterile into the container while stirring (=suspension 2). Suspension 2 is filtered for 20-30 minutes after addition. The sterile outlet valve is then opened again, and the suspension is concentrated as described previously. After about 11000 g of clear filtrate have been discharged, the outlet valve is closed and about 10107 g of precooled water for injections (11±3° C.) are again filtered sterile into the container with stirring (=suspension 3). The suspension was stirred for 20-30 min after addition. The sterile outlet valve is then again opened, and the suspension is concentrated as described previously. After about 18303 g of clear filtrate have been discharged, the outlet valve is closed. 8262 g of this suspension are then transferred from the first container into a further sterile container and then 3187 g of a 4% (m/m) mannitol solution are filtered sterile into the further container while stirring (=suspension 4). Addition is followed by stirring for 10-15 min, and then the final suspension 4 is dispensed through the suspension outlet valve (see, for example, FIG. 1, suspension outlet 7) into 10R glass vials. The dispensing solution contains not more than 10% ethanol. The molar ratio of teverelix to embonate is 2:1. The filled vials (about 3000) are placed in the lyophilizer, frozen at about −45° C. and lyophilized in vacuo at a plate temperature rising from −45° C. to +20° C. in the primary drying and at about 25° C. in the secondary drying. The freeze-drying system is then flushed with sterile nitrogen, and the vials are closed with suitable stoppers in the system and then crimp-capped. The lyophilizate is reconstituted by using 2 ml of water for injections per vial. The suspension obtained by gentle swirling can be administered s.c. or i.m.

Example 3 Production of a Sterile Suspension of D-63153 Embonate (2:1) and of a Sterile Lyophilizate of 30 mg of D-63153 Embonate Using the Separation Process by Means of a Filter

118 g of D-63153 acetate are added stepwise with continuous stirring to 3095 g of water for injection in a suitable vessel and dissolved. 10116 g of 96% (v/v) ethanol are then added with stirring. The ethanol content is subsequently adjusted to 70% (m/m) with water for injections. 16.2 g of disodium embonate are then added with continuous stirring until the disodium embonate has completely dissolved (=solution 1). 12186 g of solution 1 are subsequently transferred with the aid of a sterilizing filter (0.22 μm) into a container (see FIG. 1). The container is cooled to a temperature of 11±3° C. and kept at this temperature throughout the process. About 24972 g of precooled water for injections (11±3° C.) are then filtered sterile into the container while stirring, and a suspension of D-63153 embonate is produced (=suspension 1). Suspension 1 is stirred for 20-30 min after addition. The sterile outlet valve (see FIG. 1, liquid outlet 8) is subsequently opened, and the suspension is concentrated through the stainless steel gauze (nominal pore size: 5 μm), employed, initially without pressure and later by applying a low pressure (<0.2 bar). After about 20140 g of clear filtrate have been discharged, the valve is closed. Thereafter, about 11900 g of precooled water for injections (11±3° C.) are again filtered sterile into the container while stirring (=suspension 2). Suspension 2 is filtered for 20-30 minutes after addition. The sterile outlet valve is then opened again, and the suspension is concentrated as described previously. After about 11900 g of clear filtrate have been discharged, the outlet valve is closed and about 9263 g of precooled water for injections (11±3° C.) are again filtered sterile into the container with stirring (=suspension 3). The suspension is stirred for 20-30 min after addition. The sterile outlet valve is then again opened, and the suspension is concentrated as described previously. After about 17186 g of clear filtrate have been discharged, the outlet valve is closed. 8535 g of this suspension are then transferred from the first container into a further sterile container and then 3283 g of a 4% (m/m) mannitol solution are filtered sterile into the further container while stirring (=suspension 4). Addition is followed by stirring for 10-15 min, and then the final suspension 4 is dispensed through the suspension outlet valve (see FIG. 1, suspension outlet 7) into 10R glass vials. The dispensing solution contains not more than 10% ethanol. The molar ratio of D-63153 to embonate is 2:1. The filled vials (about 3000) are placed in the lyophilizer, frozen at about −45° C. and lyophilized in vacuo at a plate temperature rising from −45° C. to +20° C. in the primary drying and at about 25° C. in the secondary drying. The freeze-drying system is then flushed with sterile nitrogen, and the vials are closed with suitable stoppers in the system and then crimp-capped. The lyophilizate is reconstituted by using 2 ml of water for injections per vial. The suspension obtained by gentle swirling can be administered s.c. or i.m.

Example 4 Production of a Sterile Suspension of Cetrorelix Embonate (2:1) and of a Sterile Lyophilizate of 30 mg of Cetrorelix Embonate Using the Separation Process by Means of Centrifugation

1.85 g of cetrorelix acetate were dissolved in 47 ml of water for injections in a suitable vessel while stirring. Then 128 ml of 96% (v/v) ethanol were added while stirring, and subsequently the ethanol content was adjusted to 70% (m/m) with water for injections (=solution 1). 0.24 g of disodium embonate was added to 150 ml of this solution 1 while stirring. Stirring was continued for 10-15 min after the addition until the disodium embonate had completely dissolved. The centrifuge (see also FIG. 2) was loaded with in each case 8-10 containers and subsequently 2.4 ml portions of this solution were filtered sterile (0.22 μm) into a centrifuge container. 5.6 ml of water for injections were then added to each centrifugation container while stirring, and a suspension was produced (=suspension 1). The stirrer was switched off after stirring for 10 min. The complete centrifugation apparatus was controlled in a temperature range of 4-16° C. throughout the production process, and the centrifugation was carried out at 9,500 g for about 0.5 minutes. Then 5 ml of the clear supernatant solution were removed sterile by means of a suction pipe from each centrifugation container, and about 5 ml of water for injections were again added to the individual containers and stirred (=suspension 2). Centrifugation was then carried out at about 13,000 g for about 0.5 minutes. Subsequently, 5 ml portions of the supernatant solution were removed sterile by means of a suction pipe from each centrifugation container, and about 5 ml of water for injections was again added to the individual containers and stirred (=suspension 3). Finally, suspension was then carried out at about 13,000 g for about 0.5 minute, and 5 ml portions of supernatant solution were removed sterile from each centrifugation container. 2 ml of a 12.5% (w/w) sterile mannitol solution were then added to the suspension in each centrifugation container while stirring to result in an isotonic suspension with 5% mannitol (=suspension 4). The final suspensions 4 were then dispensed aseptically from the centrifugation containers into 10R vials (5 ml portions). The described procedure was repeated with new centrifugation containers until all of solution 1 was reacted. The molar ratio of cetrorelix to embonate was 2:1. The resulting approximately 60 vials were placed in the lyophilizer, frozen at about −45° C. and lyophilized in vacuo at a plate temperature rising from −45° C. to +20° C. in the primary drying and at about 25° C. in the secondary drying. The freeze-drying system was then flushed with sterile nitrogen and the vials were closed with suitable stoppers in the system and subsequently crimp-capped. 2 ml of water for injections were used to reconstitute the lyophilizate per vial. The suspension obtained by gentle swirling can be administered s.c. or i.m.

Example 5 Production of a Sterile Suspension of Cetrorelix Palmitate (1:1) and of a Sterile Lyophilizate of 30 mg of Cetrorelix Palmitate Using the Separation Process by Means of Centrifugation

1.85 g of cetrorelix acetate were dissolved in 47 ml of water for injections in a suitable vessel while stirring. Then 128 ml of 96% (v/v) ethanol were added while stirring, and subsequently the ethanol content was adjusted to 70% (m/m) with water for injections (=solution 1). 0.3 g of palmitic acid was added to 150 ml of this solution 1 while stirring (=solution 2). Stirring was continued for 10-15 min after the addition. The centrifuge was loaded with in each case 8-10 containers and subsequently 2.4 ml of this solution 2 in each case were filtered sterile (0.22 μm) into one of the centrifuge containers. 5.6 ml of water for injections were then added while stirring, and a suspension was produced (=suspension 1). Further processing was then carried out as described in Example 4, but the centrifugations were each carried out at about 19,000 g for about 15 min each time. The molar ratio of cetrorelix to palmitate was 1:1. The lyophilizate was reconstituted by using 2 ml of water for injections per vial. The suspension obtained by gentle swirling can be administered s.c. or i.m.

Example 6 Production of a Sterile Suspension of Cetrorelix Citrate (1:1) and of a Sterile Lyophilizate of 30 mg of Cetrorelix Citrate Using the Separation Process by Means of Centrifugation

1.85 g of cetrorelix acetate were dissolved in 47 ml of water for injections in a suitable vessel while stirring. Then 128 ml of 96% (v/v) ethanol were added while stirring, and subsequently the ethanol content was adjusted to 70% (m/m) with water for injections (=solution 1). 0.24 g of citric acid monohydrate was added to 150 ml of this solution 1 while stirring (=solution 2). Stirring was continued for 10-15 min after the addition. The centrifuge was loaded with in each case 8-10 containers and subsequently 2.4 ml of this solution 2 in each case were filtered sterile (0.22 μm) into one of centrifuge containers. 5.6 ml of water for injections were then added while stirring, and a suspension was produced (=suspension 1). Further processing was then carried out as described in Example 4, but the centrifugations were each carried out at about 19,000 g for about 15 min each time. The molar ratio of cetrorelix to citrate was 1:1. The lyophilizate was reconstituted by using 2 ml of water for injections per vial. The suspension obtained by gentle swirling can be administered s.c. or i.m.

Example 7 Production of a Sterile Suspension of Cetrorelix Embonate (2:1) and of a Sterile Lyophilizate of 30 mg of Cetrorelix Embonate Using the Separation Process by Means of Three-Dimensional Filter Separation

44.02 g of cetrorelix acetate are added stepwise with continuous stirring to about 1149 g of water for injections in a first suitable vessel and are dissolved. Then about 3798 g of 92% (m/m) ethanol are added while stirring. Subsequently, the ethanol content is adjusted to 70% (m/m) with 0.17 g of water for injections (=solution 1). 6.15 g of disodium embonate [86% (m/m)] is then added while stirring continuously until the disodium embonate has dissolved completely (=solution 2). 4850.0 g of solution 2 are then transferred with the aid of a sterilizing filter (0.22 m) in a further container (see FIG. 3). The container is cooled to a temperature of 11+/−3° C. and maintained at this temperature throughout the process. About 9700 g of precooled water for injections (11+/−3° C.) are then filtered sterile into the container while stirring, and a suspension of cetrorelix embonate is generated (=suspension 1). After the addition, suspension 1 is stirred for 20-30 min. The sterile outlet valve (see FIG. 3, liquid outlet 8) is then opened, and the suspension is concentrated, initially under atmospheric pressure and later by applying a slight pressure (<0.2 bar) through the stainless steel gauze employed (three-dimensional filter drum, nominal pore size: 3 μm). After about 8639 g of clear filtrate have been discharged, the valve is closed. Then a further approx. 5523 g of precooled water for injections (11+/−3° C.) are filtered sterile into the container while stirring (=suspension 2). After the addition, suspension 2 is stirred for about 10 min. The sterile outlet valve is then opened again, and the suspension is concentrated as described previously. After about 5469 g of clear filtrate has been discharged, the outlet valve is closed.

A further approx. 1956 g of precooled water for injections (11+/−3° C.) are then filtered sterile into the container while stirring (=suspension 3). After the addition, suspension 3 is stirred for about 10 min. The sterile outlet valve is then again opened, and the suspension is concentrated as described previously. After about 4338 g of clear filtrate has been discharged, the outlet valve is closed. Then 1560.1 g of a 7.4% (m/m) mannitol solution are filtered sterile into the container while stirring (=suspension 4). The addition is followed by stirring for a further 10-15 min and then the final suspension 4 is dispensed through the suspension outlet valve (see FIG. 3, suspension outlet 7) into 10R glass vials. The solution for dispensing contains not more than 10% ethanol. The molar ratio of cetrorelix to embonate is 2:1. The filled vials are placed in the lyophilizer, frozen at about −45° C. and lyophilized at a plate temperature increasing from −45° C. to +20° C. in vacuo in the primary drying and at about 25° C. in the secondary drying. The freeze-drying system is then flushed with sterile nitrogen, the vials are closed with suitable stoppers in the system and then crimp-capped. 2 ml of water for injections are used per vial to reconstitute the lyophilizate. The suspension obtained by gentle swirling can be administered s.c. or i.m.

Example 8 Production of a Sterile Suspension of Cetrorelix Embonate (2:1) and of a Sterile Lyophilizate of 30 mg of Cetrorelix Embonate Using the Separation Process by Means of Hollow Fiber Membrane Filter Separation

A suspension 1 of cetrorelix embonate is generated as in Example 1 in a suitable initial container (as component of a closed production system as shown in FIG. 4). About 3540 g of the generated suspension 1 which has been precooled to a temperature of 11+/−3° C. are employed and pumped in a closed circulation with mixing through the production system (see FIG. 4) with hollow fiber membrane filter (UMP-153 Pall Microza module with PVDF hollow fiber membrane filter, nominal pore size: 0.2 μm, Pall Corporation). The initial container is previously cooled to a temperature of 11+/−3° C. and maintained at this temperature throughout the process. Mixing is brought about by the pump/pump system and/or by a stirrer which is optionally present in the initial container. A separation process in which the suspension of cetrorelix embonate continuously passes through the filter membrane is achieved, the clear filtrate being separated on the latter (depletion). After an initial amount of 2122.7 g of filtrate has been separated, 1343.9 g of water for injections which has been precooled to a temperature of 11+/−3° C. is put into the production system with mixing, and the separation process is continued. After a second amount of 1349.9 g of filtrate has been separated, 485.6 g of water for injections which has been precooled to a temperature of 11+/−3° C. is put into the initial container with mixing, and the continuous separation process is continued until a third amount of 1903.1 g of filtrate has been separated. The final suspension of cetrorelix embonate is then mixed with sterile mannitol solution as in Example 1 and dispensed into 10R glass vials. The solution for dispensing contains not more than 10% ethanol. The molar ratio of cetrorelix to embonate is 2:1. The filled vials are placed in the lyophilizer, frozen at about −45° C. and lyophilized at a plate temperature increasing from −45° C. to +20° C. in vacuo in the primary drying and at about 25° C. in the secondary drying. The freeze-drying system is then flushed with sterile nitrogen, the vials are closed with suitable stoppers in the system and then crimp-capped. 2 ml of water for injections are used per vial to reconstitute the lyophilizate. The suspension obtained by gentle swirling can be administered s.c. or i.m.

Example 9 Determination of the pH of Cetrorelix Base and Teverelix Base

The determination of the pH of a saturated solution of cetrorelix base and teverelix base was carried out using a WTW pH meter level 1 pH meter from inoLab and an Idrolyte, pH 1-11; 0° C.-60° C., Order No. 6.0224.100 electrode from Metrohm at room temperature (22° C.).

A total of 1.5 ml of water for injections was added in portions to 74.56 mg of cetrorelix base in a vial while stirring until a cloudy, very viscous solution was formed. The pH of this solution was measured at different times over a period of up to 24 hours. The pH reached a plateau (pH=1.2) after about 25 min and was still there after 24 hours. The pH of the water for injections (blank) was 6.5. A total of 0.75 ml of water for injections was added in portions to 47.26 mg of teverelix base in a vial while stirring until a saturated clear, very viscous solution was formed. The pH of this solution was measured at various times over a period of up to 24 hours. The pH reached a plateau (pH=8.3) after about 30 min and was still there after 24 hours. The pH of the water for injections (blank) was 6.5.

Example 10 Measurement of the Particle Size Distribution of the Particles of a Suspension of Cetrorelix Embonate (2:1)

The particle size distribution of the particles of a suspension of cetrorelix embonate (2:1) was carried out by laser diffractrometry using a Master Sizer X, a small volume unit MSX 1 and a “flow cell” from Malvern Instruments and the following parameters: focus: 300 mm (range 1.2-600 μm), polydisperse model, active beam length: 2.4 mm, obscuration: 10-20%, dispersion medium: water, stirring speed: 3250 rpm (level: 6.5).

From a cetrorelix embonate (2:1) suspension produced as in Example 1, before carrying out the separation process using a filter, sufficient suspension was added in portions while stirring to 95 ml of water for injections which was introduced into the MSX 1 stirred cell to result in an obscuration of 10-20%. Stirring was then continued for a further 1.5 min before the measurement was carried out while stirring. FIG. 5 shows the result of the measurement of the particle size distribution. The unimodal distribution is proof of the absence of agglomeration of the particles of the cetrorelix embonate peptide complex and the absence of sediments which are not or are only partially resuspendable. On the basis of the measured particle size distribution, a stainless steel gauze (nominal pore size: 5 μm) was used as filter for the separation process.

30 mg of a cetrorelix embonate (2:1) lyophilizate produced as in Example 1 were reconstituted analogously in 2 ml of water for injections, a suspension was produced by gentle swirling for 3 min, and the particle size distribution was measured analogously. The unimodal distribution proves the absence of agglomeration of the particles of the cetrorelix embonate peptide complex and complete resuspendability of the lyophilizate.

Example 11 Determination of the Stability of Various Cetrorelix Embonate Formulations

The stability of the following different cetrorelix embonate formulations was investigated in relation to the timing of their inhomogeneity, i.e. the occurrence of a visually recognizable two-phase mixture:

-   -   A) P85P002A (suspension according to the invention),     -   B) D-20762-PRT/a [cetrorelix embonate (1:1.6) microparticle         formulation according to DE 43 42 092],     -   C) D-20762-PRT/a [cetrorelix embonate (1:1.6) microparticle         formulation according to Felberbaum et al. (1998)].

The formulations were reconstituted as lyophilizates with in each case 2 ml of water for injections—in the case of A) and B)—and 2 ml of SM1 medium [176.5 mg of mannitol, 21.1 mg of polysorbate 80, 83.9 mg of carboxymethylcellulose sodium, 31.4-52.5 mg of sodium hydroxide (0.1N solution) and water for injections ad 4.3 g)]—in the case of C)—, swirled for about 1-2 min and then the stability was observed visually over a period of 15 minutes. Table 1 represents the visual observed stabilities of the abovementioned cetrorelix embonate formulations at various times.

TABLE 1 Time Formulation A) Formulation B) Formulation C) 0 min completely immediate suspension, initial signs homogeneous inhomogeneity, two- of incipient suspension, no visually phase mixture inhomogeneity recognizable inhomogeneity 2 min completely two-phase mixture, two-phase mixture homogeneous formation of a becoming clearer, suspension, no visually sediment sediment formation not recognizable yet evident inhomogeneity 4 min completely two-phase mixture, two-phase mixture, homogeneous progressive formation indications of sediment suspension, no visually of a sediment formation recognizable inhomogeneity 6 min completely two completely two-phase mixture, homogeneous separated phases: formation of a suspension, no visually liquid phase and sediment recognizable sediment inhomogeneity 8 min completely two completely two-phase mixture, homogeneous separated phases: progressive formation suspension, no visually liquid phase and of a sediment recognizable sediment inhomogeneity 10 min  completely two completely two-phase mixture, homogeneous separated phases: progressive formation suspension, no visually liquid phase and of a sediment recognizable sediment inhomogeneity 12 min  completely two completely two-phase mixture, homogeneous separated phases: progressive formation suspension, no visually liquid phase and of a sediment recognizable inhomogeneity sediment 15 min  completely two completely two completely homogeneous separated phases: separated phases: liquid suspension, no visually liquid phase and phase and sediment recognizable sediment inhomogeneity

It is clearly evident from Table 1 that the suspension A) according to the invention is stable over the period considered and no inhomogeneity to give a two-phase mixture occurs. By contrast, with the microparticle formulations B) and C) there is immediate or very rapid inhomogeneity to form two-phase mixtures with distinct sediment formation.

Example 12 In Vitro Active Ingredient Release from Various Cetrorelix Embonate Formulations

The in vitro active ingredient release from various cetrorelix embonate formulations was carried out as follows. An ERWEKA DFZ60 flow cell system from Erweka was employed. The cell size was 22.6 mm in each case. The flow medium used was physiological Ringer's solution (8.6 g NaCl+0.3 g KCl+0.25 g CaCl₂ in 1 l of water for injections), with a flow rate of 0.3 ml/min. The temperature was 37° C. during the procedure. Glass beads (diameter: 0.4-0.6 mm) from Sartorius were used. The flow cells were prepared in each case in layers from the bottom to the top as follows: a glass ball with a diameter of 5 mm, about 2 cm of absorbent cotton, a glass frit (diameter: 2.5 cm), a layer of about 6 g of glass beads, in which the respective reconstituted formulations were uniformly distributed with a 2 ml disposable syringe with hypodermic needle (0 0.90×40 mm), and an additional layer of 1-2 g of glass beads.

The following 30 mg cetrorelix embonate formulations were employed in independent duplication determinations: (i) P85P002A (suspension according to the invention), (ii) DJ5 [cetrorelix embonate (1:1.6) microparticle formulation according to DE 43 42 092 and Felberbaum et al. (1998)], (iii) 9612-002/05-g (suspension obtainable according to DE 100 40 700).

P85P002A and 9612-002/05-g were each reconstituted as lyophilizates with 2 ml of water for injection and swirled for 1-2 min before they were injected into the layer of glass beads. DJ5 was resuspended in 2 ml of SM1 medium [176.5 mg of mannitol, 21.1 mg of polysorbate 80, 83.9 mg of carboxymethylcellulose sodium, 31.4-52.5 mg of sodium hydroxide (0.1N solution) and water for injections ad 4.3 g)] and likewise swirled for about 1-2 min before the injection. Fractions of the flow medium which had flowed through the flow cell system were collected over a period of 191 hours, and the amount of cetrorelix released in each case was determined by HPLC using an external cetrorelix standard. The result of the HPLC determination is shown in FIG. 6 as the respective cumulative amount of active ingredient released over the entire period of 191 hours. The distinctly improved active ingredient release of the suspensions according to the invention is unambiguously evident.

Example 13 Comparison of the Testosterone Suppression in Male Persons

60 mg of a cetrorelix embonate (2:1) lyophilizate produced as in DE 100 40 700, and 60 mg of a cetrorelix embonate (2:1) lyophilizate produced according to the invention were each reconstituted in 4 ml of water for injections and administered parenterally as i.m. dose to men. The cetrorelix plasma concentrations reached, and the testosterone suppressions, were determined for both formulations after in each case 1 week and 2 weeks compared with the initial level at the time of administration (week 0) (study 3107: suspension produced and administered according to DE 100 40 700; study JAP: suspension produced and administered according to the invention).

FIG. 7 shows the determined testosterone suppression, which has been depicted normalized (initial levels in each case at the time of administration (week 0)=100%).

The more advantageous hormone suppression of the suspension produced according to the invention is evident from FIG. 7. Thus, the suspension according to the invention brings about marked hormone suppression both after one and after two weeks.

The above written description of the invention provides a manner and process of making and using it such that any person skilled in this art is enabled to make and use the same, this enablement being provided in particular for the subject matter of the appended claims, which make up a part of the original description.

As used above, the phrases “selected from the group consisting of,” “chosen from,” and the like include mixtures of the specified materials. Terms such as “contain(s)” and the like as used herein are open terms meaning ‘including at least’ unless otherwise specifically noted.

All references, patents, applications, tests, standards, documents, publications, brochures, texts, articles, etc. mentioned herein are incorporated herein by reference. Where a numerical limit or range is stated, the endpoints are included. Also, all values and subranges within a numerical limit or range are specifically included as if explicitly written out.

The above description is presented to enable a person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the preferred embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Thus, this invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. 

1. A sterile suspension of a slightly soluble basic peptide complex obtained by a process comprising: under aseptic conditions, a) i) mixing a sterile solution comprising at least one of a salt or a complex of a basic peptide and of an aliphatic or aromatic organic carboxylic acid and/or salts thereof in a solvent or solvent mixture, optionally with the addition of solubility-increasing and/or agglomeration-suppressing additives, or ii) combining and mixing a sterile solution of a salt or complex of at least one basic peptide in a solvent or solvent mixture and a sterile solution of an aliphatic or aromatic organic carboxylic acid and/or salts thereof in a solvent or solvent mixture, optionally with the addition of solubility-increasing and/or agglomeration-suppressing additives, b) generating, by mixing and addition of a diluent or diluent mixture in one or more steps, a suspension of a slightly soluble basic peptide complex of the basic peptide with the carboxylic acid, which complex precipitates at the latest after addition of the diluent or diluent mixture, c) depleting, while mixing in a continuous or stepwise separation process, the solvent or solvent mixture, free non-peptide ions, excess carboxylic acid and optionally added solubility-increasing and/or agglomeration-suppressing additives in the resulting suspension, with the liquid content of the suspension being reduced and optionally further diluent or diluent mixture being added in one or more steps, and d) optionally adding to the slightly soluble basic peptide complex, while mixing the sterile suspension during c) and/or thereafter, one or more pharmaceutical excipients, carriers and/or bulking agents.
 2. A sterile lyophilizate of a slightly soluble basic peptide complex obtained by a process comprising: a) i) mixing a sterile solution comprising at least one of a salt or a complex of a basic peptide and of an aliphatic or aromatic organic carboxylic acid and/or salts thereof in a solvent or solvent mixture, optionally with the addition of solubility-increasing and/or agglomeration-suppressing additives, or ii) combining and mixing a sterile solution of a salt or complex of at least one basic peptide in a solvent or solvent mixture and a sterile solution of an aliphatic or aromatic organic carboxylic acid and/or salts thereof in a solvent or solvent mixture, optionally with the addition of solubility-increasing and/or agglomeration-suppressing additives, b) generating, by mixing and addition of a diluent or diluent mixture in one or more steps, a suspension of a slightly soluble basic peptide complex of the basic peptide with the carboxylic acid, which complex precipitates at the latest after addition of the diluent or diluent mixture, c) depleting, while mixing in a continuous or stepwise separation process, the solvent or solvent mixture, free non-peptide ions, excess carboxylic acid and optionally added solubility-increasing and/or agglomeration-suppressing additives in the resulting suspension, with the liquid content of the suspension being reduced and optionally further diluent or diluent mixture being added in one or more steps, and e) lyophilizing the sterile suspension of the slightly soluble basic peptide complex obtained in step c) and optionally adding to the lyophilizate obtained one or more pharmaceutical excipients, carriers and/or bulking agents.
 3. A sterile lyophilizate of a slightly soluble basic peptide complex obtained by a process comprising: a) i) mixing a sterile solution comprising at least one of a salt or a complex of a basic peptide and of an aliphatic or aromatic organic carboxylic acid and/or salts thereof in a solvent or solvent mixture, optionally with the addition of solubility-increasing and/or agglomeration-suppressing additives, or ii) combining and mixing a sterile solution of a salt or complex of at least one basic peptide in a solvent or solvent mixture and a sterile solution of an aliphatic or aromatic organic carboxylic acid and/or salts thereof in a solvent or solvent mixture, optionally with the addition of solubility-increasing and/or agglomeration-suppressing additives, b) generating, by mixing and addition of a diluent or diluent mixture in one or more steps, a suspension of a slightly soluble basic peptide complex of the basic peptide with the carboxylic acid, which complex precipitates at the latest after addition of the diluent or diluent mixture, c) depleting, while mixing in a continuous or stepwise separation process, the solvent or solvent mixture, free non-peptide ions, excess carboxylic acid and optionally added solubility-increasing and/or agglomeration-suppressing additives in the resulting suspension, with the liquid content of the suspension being reduced and optionally further diluent or diluent mixture being added in one or more steps, d) optionally adding to the slightly soluble basic peptide complex, while mixing the sterile suspension during c) and/or thereafter, one or more pharmaceutical excipients, carriers and/or bulking agents e) lyophilizing the sterile suspension of the slightly soluble basic peptide complex obtained in step d).
 4. A pharmaceutical formulation for parenteral administration, comprising at least one sterile suspension of a slightly soluble basic peptide complex as claimed in claim
 1. 5. A pharmaceutical composition comprising: an aseptic reaction product of a sterile solution of a cetrorelix salt and an organic carboxylic acid or salt in at least one solvent with at least one sterile diluent, wherein the reaction product is depleted of solvent, of free salt ions and of free carboxylic acid.
 6. A pharmaceutical composition comprising a slightly soluble cetrorelix salt or complex, wherein the cetrorelix salt is free of any tracers of ion exchange resin or of any materials embedded therein, and substantially free of solvent, free non-peptide ions, and/or excess carboxylic acid.
 7. The pharmaceutical composition of claim 6, wherein greater than 50% of particles of the cetrorelix salt have a particle diameter less than 20 μm.
 8. The pharmaceutical composition of claim 7, wherein greater than 90% of the particles of the cetrorelix salt have a particle diameter of less than 100 μm.
 9. A slightly soluble cetrorelix salt composition comprising about 30 mg cetrorelix salt, wherein the composition cumulatively releases greater than 15 mg of the Cetrorelix salt in vitro over 160 hours. 